7 15.2 The actual ages of rocks and fossils mark geologic timeRadiometric datingMeasures the decay of radioactive isotopesCan gauge the actual ages of fossils and the rocks in which they are found

8 15.3 Continental drift has played a major role in macroevolutionIs the slow, incessant movement of Earth’s crustal plates on the hot mantleEdge of one plate being pushed over edge of neighboring plate (zones of violent geologic events)Antarctic PlateAustralian PlateSplit developingIndian PlateEurasian PlateNorth American PlateSouth American PlateNazca PlatePacific PlateArabian PlateAfrican PlateFigure 15.3A

9 The formation of Pangaea Altered habitats and triggered extinctionsFigure 15.3B65135245Millions of years agoPaleozoicMesozoicCenozoicNorth AmericaEurasiaAfricaSouthAmericaIndiaAntarcticaAustraliaLaurasiaGondwanaPangaea

10 The separation of the continents Affected the distribution and diversification of organismsNorthAmericaSouthEuropeAsiaAfricaAustralia= Living lungfishes= Fossilized lungfishesFigure 15.3CFigure 15.3D

15 PHYLOGENY AND SYSTEMATICS15.6 Phylogenies are based on homologies in fossils and living organismsPhylogeny, the evolutionary history of a groupIs based on identifying homologous and molecular sequences that provide evidence of common ancestry

16 Analogous similarities Result from convergent evolution in similar environmentsFigure 15.6

17 SystematicsInvolves the analytical study of diversity and phylogeny

18 15.7 Systematics connects classification with evolutionary historyTaxonomists assign a binomialConsisting of a genus and species name, to each speciesA genusMay include a group of related species

25 Studies of ribosomal RNA sequences Have shown that humans are more closely related to fungi than to green plantsStudentMushroomTulipCommon ancestorFigure 15.9B

26 DNA Comparisons Molecular comparisons of nucleic acidsOften pose technical challengesCan reveal the most fundamental similarities or differences between species

27 Molecular Clocks Some regions of DNAChange at a rate consistent enough to serve as molecular clocks to date evolutionary events

28 Genome Evolution Homologous genes Are found in many species HumanChimpanzeeGorillaOrangutanCommon ancestorFigure 15.9C

29 15.10 Arranging life into kingdoms is a work in progressIn the five-kingdom systemProkaryotes are in the kingdom MoneraEukaryotes (plants, animals, protists, and fungi) are grouped in separate kingdomsMoneraProtistaPlantaeFungiAnimaliaEarliestorganismsProkaryotesEukoryotesFigure 15.10A